This invention relates to metal inert gas welding and more particularly to a welding torch with an integral optical system which directly views the weld area.
Good arc welds are achieved by controlling weld current, arc voltage, weld penetration, centering of the weld puddle over the weld joint, weld bead lay rate, etc. When welding manually or by machine, welds can be of marginal quality due to limited visual access to the weld region and the necessity of controlling the weld parameters on the basis of past experience or predicted part geometry. For consistently good welds, some means is necessary for real time sensing of weld puddle characteristics and for using this sensed information as feedback to control the weld parameters to achieve optimum welds.
Some welding experiments for gas tungsten arc welding have been conducted at Ohio State University Center for Welding Research in which a strictly laboratory setup was used to optically observe the weld puddle during the welding operation. Subsequent developments and a viewing system in which the optical axis coincides with the weld torch and electrode axis were reported by R. W. Richardson et al. at the ASME Winter Annual Meeting, Nov. 14-19, 1982.
An arc welding torch that has a built-in vision sensor and a configuration suitable for industrial welding is described in copending application Ser. No. 401,471, filed July 26, 1982, now abandoned, and continuation application Ser. No. 619,432, filed June 11, 1984, now U.S. Pat. No. 4,488,032 A. W. Case, Jr., N. R. Kuchar and D. C Peroutky. This torch presents minimum obstruction to passage of light to the optical lens; the slim profile tungsten electrode holder is out of focus and not seen in the image of the weld puddle and weld area. When coupled to a remote video camera and welding controller, the torch-vision system permits control of torch manipulation and of the weld process. While disclosed for both GTA and GMA welding, the illustrated embodiments are the former. This and other subsequently filed applications are assigned to the same assignee.